The invention relates to an arrangement of microstructured elements according to the preamble of claim 1.
In microtechnology, there is the problem of precisely positioning individual, already existing components with respect to each other before securing them. Frequently, for example in microoptics, the permissible tolerances fall within the micrometer or even the submicrometer range. Currently, primarily active adjusting processes are typically used. Active in this connection means that the individual components are brought into their final position during the active operation of the system or subsystem. An example for this is the coupling of a semiconductor laser to an optical fiber. The fiber is shifted until the intensity of the light guided in the fiber reaches a maximum. Active adjustment processes are difficult to automate and therefore expensive. This impedes the continued expansion of microtechnology systems.
In many cases, active adjustment is not possible, or extremely difficult, for technical reasons. Particularly if many components are to be arranged on a small area, there is frequently no space to accommodate adjusting tools in this area to shift the components with micrometer precision. Attempts have therefore been made for some time to use passive adjustment for the individual components. In passively adjusted systems, the outside dimensions of the individual components or subsystems are so exact, or the limit stop edges so precisely executed, that the components can be positioned next to each other, or inserted into each other, to permit immediate optimal operation of the system, i.e., without requiring any further adjustment steps.
Passive adjustment in microtechnology has thus far primarily failed because the components to be positioned are not manufactured with the requisite exactness. As a result, simple positioning together or insertion of components has been successful in only a few special cases. For example, for laser-fiber coupling, spherical lenses on silicon substrates can be inserted in pyramidal recesses produced by anisotropic etching processes. The spherical lenses touch the etched recesses at only four points. Due to their simple geometric shape, spherical lenses can be manufactured very precisely at low cost. Optimizing the etching process has meanwhile also made it possible to produce recesses in silicon, which have the requisite tolerances of a few tenths of a micrometer to make such passive adjustment possible.
Optical fibers, too, can be very precisely positioned on silicon substrates if they are placed in V-shaped etched channels. The optical fibers touch these channels only along two lines and not along an area.
EP 0 638 829 A1 discloses a concept for positioning optical components on a (silicon) substrate. As indicated in FIG. 74, for example, terrace shaped shoulders, onto which the component to be positioned is placed, are etched out of the substrate. As a result, the height of the component In relation to the substrate surface is precisely defined. The lateral alignment of the component is achieved by limit stops on both sides of the component The limit stops are made as surfaces arranged perpendicularly to the substrate surface. Between the limit stops and the component to be inserted, there must be a clearance fit so that the component can still be Inserted. Since It is difficult to insert the component into the gap between the two limit stops, an alternative is proposed where the component is laterally adjusted by means of flip chip bonds. Flip chip bonding, however, requires additional process steps. Furthermore, this technique cannot be used for all components.